Signal devices



March 22, 1960 L. ARNESON 2,930,017

SIGNAL DEVICES Filed NOV. 5, 1958 JNVENTOR. LEIF ARNESEN ATTORNEY UnitedStates Patent v SIGNAL DEVICES Leif Arneson, Minneapolis, Minn.,assignor to Minneapolis-Honeywell Regulator Company, Minneapolis, Minn.,a corporation of Delaware Application November 5, 1958, Serial No.772,118 6 Claims. (Cl. 338-91) This invention relates to the field ofelectrical instruments, and more specifically to non-linear voltagedividers. It is known to construct voltage dividers so that theresistance gradient for a given slider displacement is not everywherethe same, and it is also known to construct voltage dividers withuniform resistance gradients and with mechanical movement between theslider and its drive shaft which introduces nonlinearity into the motiontransmitted. Devices of the latter type have heretofore required gearmeans, however, and this introduces inaccuracies due to imperfect gearcutting, to back lash, and in general to the difliculties inherent ingeared mechanism.

The principal object of this invention is to provide a voltage divider,having a linear resistance element and a non-linear output, in which nogears are required. Another object of the invention is to provide avoltage divider in which a four bar linkage and a cam and follower areinserted between the drive shaft and the slider, to give a desirednon-linearity of operation. A specific object of the invention is toprovide a novel mechanical linkage.

Various other objects, advantages, and features of novelty notparticularly enumerated above which characterize my invention arepointed out with particularity in the claims annexed hereto and forminga part hereof. However, for a better understanding of the invention, itsadvantages, and objects attained by its use, reference should be had tothe subjoined drawing, which forms a further part hereof, and to theaccompanying descriptive matter, in which I have illustrated anddescribed a preferred embodiment of my invention.

In the drawings Figure 1 is a schematic showing of a voltage divideraccording to the invention, and Figures 2 and 3 are longitudinal andtransverse sectional views of one physical embodiment of the invention.

Figure 1 shows an input shaft pivoted for rotation about an axis 11, andan output shaft 12 pivoted about the same axis. Shaft 10 carries a link13 and shaft 12 carries a link 14. Pivoted to links 13 and 14 about axes15 and 16 respectively are a pair of further links 17 and 20 having acommon pivotal axis 21. A circular cam follower 22 is pivoted about axis21, and moves in contact with a cam 23. A spring 24 acts on links 13 and14 to decrease the angle between them, and thus urge follower 22 intocontact with cam 23. A circular resistance element 25 is mountedconcentric with axis 11, and a slider 26 is carried by link 14 forcontinuous engagement with element 25.

It will be evident that as long as cam 23 defines a circle about axis11, rotation of input shaft 11 results in rotation of output shaft 12through the same angle. However if cam 23 is not a circle, movement ofinput shaft 10 results in a greater rotation of output shaft 12 if theradius of the cam about axis 11 is decreasing and less rotation of theoutput shaft if the radius is increasing. By suitably designing the cam,the desired nonlinearity 5 2,930,017 Patented Mar. 22, 1960 may beinserted between shaft 11 and slider 26, even to the extent of reverseoperation.

Figures 2 and 3 show a preferred embodiment of the invention, elementsidentified in Figure 1 being given the same numbers in Figures 2 and 3.

Input shaft 10 is shown to pass through a central hearing hole in acover 30, and to be pivoted in a boss 31 extending upward from the base32 of a casing 33. Link 14 is freely pivoted on the lower reduced end ofshaft 10, which thus functions as shaft 12 of Figure 1, and an aperture34 is provided in link 14 to receive the end of spring 24. Slider 26 isshown as welded to link 14 and as engaging the annular resistanceelement 25 which is received in a recess in casing 33. Link 13 is shownas fixed to shaft 10 and the other end of spring 24 is received by ahole in the link. Cam 23 is shown as carried on a shoulder in housing33, for engagement by cam follower 22; one outline for cam 23 is bestshown in Figure 2.

Numerous objects and advantages of my invention have been set forth inthe foregoing description, together with details of the structure andfunction of the invention, and the novel features thereof are pointedout in the appended claims. The disclosure, however, is illustrativeonly, and I may make changes in detail, especially in matters of shape,size and arrangement of parts, within the principle of the invention, tothe full extent indicated by the broad general meaning of the terms inwhich the. appended claims are expressed.

I claim as my invention:

1. Apparatus of the class described comprising, in combination: a fourbar linkage including an input link andi an output link, having a firstcommon pivotal axis and: a pair of intermediate pivotal axes, and a pairof inde-- pendent links, having a second common pivotal axis andi a pairof independent pivotal axes common with the.- independent pivotal axesof said input and output links: means for causing rotation of said inputlink; spring; means continuously acting to maximize the distance betweensaid common axes; cam and follower means for limiting said distance, sothat rotation of said output link is linear with rotation of said inputlink when said distance remains constant, and becomes nonlinear whensaid distance varies; a voltage divider including a resistance memberand a contact member; and means connee-ting said output link to saidvoltage divider for causing relative movement between said members.

2. Apparatus of the class described comprising, in combination: a fourbar linkage including an input link and an output link, having a firstcommon pivotal axis and a pair of independent pivotal axes, and a pairof intermediate links, having a second common pivotal axis and a pair ofintermediate pivotal axes common with the independent pivotal axes ofsaid input and output links; spring means continuously acting tominimize the angle between said input and output links and hence tomaximize the distance between said common axes; means for causingrotation of said input link; means for limiting said distance includinga cam extending around said first common axis and a cam follower carriedby said second common axis; a voltage divider including a circularresistance member and a contact member rotatable with respect thereto;and means connecting said output link to said contact member, so thatrotation of said contact member is linear with rotation of said inputlink when said distance remains constant, and becomes nonlinear whensaid distance varies.

3. Apparatus of the class described comprising, in com bination: a fourbar linkage including an input link and. an output link, having a firstcommon pivotal axis and a pair of independent pivotal axes, and a pairof interme'di-- ate links, having a second common pivotal axis and apair of intermediate pivotal axes common with the indeendent pivota axesct said ir tan output, links; mea

'for causing rotation of said input link; spring means continuouslyacting to minimize the angle between said input andoutput links andhence to. maximize thedistance. between said common axes; means 'iEorlimiting said distance including a camv extending around said firstcommon axis; andav cam follower carried. by said, second common axis; avoltage divider including a. circular. resistance memberand a contactmember rotatable. with respect thereto; means mounting said resistancemember so. that its center is substantially on said first common axis;andmeans, connecting said output link to said contact. member, so thatrotation of said contact member is linear with rotation of said inputlink when said. distance remainsconstant and becomes nonlinear when.said distance varies.

4. Apparatus of the class described comprising, in combination: a fourbar linkage, including an input link and-v an output link, having a.first common, pivotal. axis, andv a. pair ofindependent pivotal axes,and a. pair. of intermediate links, having a. second common pivotal axisand. apair of independent, pivotal axes. common. with. the, independentpivotal axes of saidv input and. output links; means for causingrotation of said. input links; spring. means continuously actingbetweensaid input andoutput links to minimize the angle therebetween andhence to, maximize the distancebetween said common, axes; means. forlimiting said. distance, including a cam extending around saidfirstcommon axis and a. cam follower. carried. by. said; second common axis;vavoltagc. divider including a circular resistance member and. a, contactmember rotatable with respect thereto; andmeans connfict ng said' outputlink tosaidcontact member, so that rotation of said" contact member. is.linear witlzrtherotationofiv said; input link when. said. distanceremains constant andbecpmesnonlinear whensaid distance varies.

5, Apparatus oi the class-described comprising,in c.0111: bination: afour. bar linkageincluding an input link: and; ncu ut ha n a r omm n. pv al. xis. an a pair. or independent pivotal. axes, and a pair. ofinter.-. mediate links,.having a second commonpivotal axis and.

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9.1981! oi. intermediate. pivotal axes common with the independentpivotal axes of said input and output links; means for causing rotationof said input links; spring means continuously acting to minimize theangle between said input and output links and hence to maximize thedistance between said common axes; means for limiting said distanceincluding a cam extending around said first common axis and a camfollower pivoted about said second common axis; a voltage dividerincluding a circular resistance member and a contact member rotatabl'ewith respect-thereto; andmeans connecting said output link to saidcontact member, so that rotation of said contact member is linear withrotation of said input link when .said distance remains constant andbecomes nonlinear when said distance varies.

6. Apparatus of the class described comprising, in combination: a fourbar linkage including an input link and anolltputlink having a. first.common pivotal axis and a pair. oflindependent, axes, and. apair ofintermediate links having: a second. common pivotal axis. anda pair oiinde-. pendent pivotal axes commonrwith the indep'endent pivotaLaXeso'f'said input. and output links;.-means for. causing rotation, oi' said}input links; spring means continuouslyacting to minimize. the anglebetween said input andouta putlinks and hence. tomaximize the distance.between: said common.axes.;.means for limiting said distance. including;acamextendingaround said first common axis'and-acam: follower pivotedabout said! second common axis between. said, intermediate. links.;. avoltage divider including. a. circular resistance member anda contactmember. rotata-- b le withrespect thereto; and. means. connecting. saidoutputljink; to said contact member, so that rotation. ofts'aidcontactmemher is linear with rotation of said input link. when saiddistance. remains constant and; becomes non linear when, said distancevaries.

References Cited in thefile of. this patent UNITED STATES- PATENTS2,471,315 Dehmel May 24,.1949'

